Decided to replace my FC5 install with FC6 (what an idiot) and expected trouble with the nvidia driver as usual, but this was a bit beyond the norm.

Here is a summary of what it took for me to get it to work in case it helps someone else; this is derived from lots of hints from other messages around the place, but I could not find a consolidated set of instructions.

Bottom line is xen kernels will not work, linux/config.h is no longer present in kernel development sources and nvidia installer expects it, and explicit specification of path to kernel sources is required since nvidia installer cannot find them.

Just used the old FC5/nvidia xorg.conf that had been working before and it still works just fine.

Tried the beta 9625 driver and it works too ... this time the xorg.conf phase did not crash (whether having in place the xorg.conf from the initial FC6 install, or my old one, before running the installer).

You know, it really is a whole lot easier to install the driver RPM from Livna:http://rpm.livna.org/
Install their RPM to setup the repository (http://rpm.livna.org/rlowiki/UsingLivna) and a quick:
yum install kmod-nvidia
will get you setup. After it installs, just restart X. It even updates when the kernel is updated (as long as the package has been built at the time, of course). And if you want the beta driver:
yum --enablerepo=livna-testing install kmod-nvidia

I was not able to get the livna rpm installed on an x86_64 FC6 install. I also did get it working throught the nvidia installer (which rebuilt the driver as part of the install), with just a single nagging annoyance left.....

It took a lot of work to install 8776 on my FC6 system. (The nvidia driver worked fine on FC5 and earlier.) Now it's installed but whenever I try to run mplayer, xine, or kaffeine to display HDTV .ts streams, the system ALWAYS freezes within a few seconds. The X11 freeze is so bad, I can't even do a ctrl alt F! to get to a text consol. So the system with FC6 is unusable for viewing HDTV.